A hot-melt benzoxazine resin composition, prepreg, composite material and preparation method thereof

Abstract

The present invention provides a hot-melt benzoxazine resin composition, a prepreg, a composite material and a preparation method thereof, wherein the hot-melt benzoxazine resin composition comprises the following components by weight: 30-80 parts of benzoxazine resin, 10-50 parts of epoxy resin, 10-30 parts of toughening agent, 2-15 parts of flame retardant, 10-25 parts of curing accelerator and 1-15 parts of epoxy diluent. The hot-melt benzoxazine resin composition, prepreg, composite material and a preparation method thereof have the characteristics of high heat resistance, strong mechanical properties, good flame retardancy, low product porosity and the like, and meet the requirements of aviation applications.

Description

Technical Field

[0001] The invention belongs to the field of composite materials, and in particular relates to a hot-melt benzoxazine resin composition, a prepreg, a composite material and a preparation method thereof. Background Art

[0002] Polybenzoxazine is a thermosetting resin. It has many characteristics such as high modulus, high temperature resistance, high flame retardancy, low dielectric constant, low surface energy, etc. At the same time, no small molecules are released during the curing process of benzoxazine, and the porosity is low after curing and it has good mechanical properties. However, the high curing temperature and long curing time of benzoxazine resin greatly limit its application scope and scale. Therefore, it is of great practical significance to reduce the curing temperature and shorten the curing time of benzoxazine resin while maintaining the excellent heat resistance and mechanical properties of benzoxazine resin.

[0003] Prepreg is an intermediate for preparing composite materials. Its preparation methods can be divided into solvent impregnation method and hot melt method. Compared with the solution impregnation method, the hot melt method avoids many negative effects caused by the presence of solvents and has the advantages of high production efficiency, easy control of glue content, no environmental pollution, and good appearance quality.

[0004] The hot melt process requires the base resin to have a low softening point and good viscosity, which is conducive to the preparation and laying of prepregs. At the same time, during the resin curing process, the viscosity of the base resin cannot be too low to avoid excessive glue flow. Benzoxazine resin has problems such as poor room temperature viscosity and too low viscosity at high temperature, and cannot be directly used in the hot melt process. Therefore, it is necessary to modify the benzoxazine resin so that it can meet the process requirements of hot melt prepreg preparation.

[0005] For example, the Chinese patent literature with publication number CN111892728A discloses a method for preparing a benzoxazine resin hot-melt prepreg for an autoclave molding process, and reduces the coating temperature by adding an appropriate organic solvent to the resin glue, improves the poor film-forming property of the resin and the low adhesion of the prepreg at room temperature, and obtains a benzoxazine resin prepreg suitable for autoclave molding with good processability. However, the addition of organic solvents will cause environmental pollution, and is not conducive to the control of product quality, and the high porosity will cause the mechanical properties of the material to be greatly reduced. The Chinese patent literature with publication number CN109354825A discloses a high temperature resistant hot-melt benzoxazine resin and a preparation method thereof, and the benzoxazine resin is modified by a blending copolymerization method to obtain a benzoxazine resin system that satisfies the hot-melt prepreg, but the curing temperature of the benzoxazine resin system is high and its comprehensive performance benchmark aviation applications needs to be improved. Summary of the invention

[0006] The technical problem solved by the present invention is to provide a hot-melt benzoxazine resin composition, a prepreg, a composite material and a preparation method thereof, in order to overcome the problems of high curing temperature of benzoxazine resin and poor processability of prepreg prepared by hot-melt method.

[0007] In order to solve the above problems, the first aspect of the present invention provides a hot-melt benzoxazine resin composition, comprising the following components in parts by weight:

[0008] 30-80 parts of benzoxazine resin, 10-50 parts of epoxy resin, 10-30 parts of toughening agent, 2-15 parts of flame retardant, 10-25 parts of curing accelerator and 1-15 parts of epoxy diluent.

[0009] Preferably, 70 parts of benzoxazine resin, 15-30 parts of epoxy resin, 10-20 parts of toughening agent, 10-15 parts of flame retardant, 20-25 parts of curing accelerator and 10-15 parts of epoxy diluent.

[0010] Preferably, the benzoxazine resin is a diamine-type benzoxazine resin; the epoxy resin is a mixture of one or more of AG-80 aliphatic epoxy resin, AFG-90 or TDE-85 mixed epoxy resin; the toughening agent is one or more of PEEK, PES, PSF and PEI; the flame retardant is one or more of aluminum hydroxide, magnesium hydroxide, magnesium oxide, ammonium polyphosphate, tetrabromobisphenol A and decabromodiphenylethane; the curing accelerator is one or more of aliphatic amine, alicyclic amine, aromatic amine, imidazole, diethylimidazole and methylimidazole; the epoxy diluent is one or more of ED-503, ED-506, ED-523T, ED-509S, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether and neopentyl glycol diglycidyl ether.

[0011] A second aspect of the present invention provides a method for preparing the hot-melt benzoxazine resin composition, comprising the following steps:

[0012] The benzoxazine resin is melted; and the melted benzoxazine resin is mixed with the epoxy resin, the toughening agent, the flame retardant, the curing accelerator and the epoxy diluent to obtain the hot-melt benzoxazine resin composition.

[0013] Preferably, the preparation method of the hot-melt benzoxazine resin composition specifically comprises the following steps:

[0014] S1: melting the benzoxazine resin;

[0015] S2: melting the toughening agent into the epoxy resin;

[0016] S3: mixing the melted benzoxazine resin, the toughening agent melted in the epoxy resin, the flame retardant, the epoxy diluent and the curing accelerator;

[0017] S4: grinding the obtained mixture to obtain the benzoxazine resin composition;

[0018] The heating temperature when melting the benzoxazine resin in step S1 is 60-140° C., and the heating time is 1-4 h; the melting temperature when melting the toughening agent in the epoxy resin in step S2 is 100-150° C.; when grinding the mixture in step S4, the number of roller grinding times is 1-4 times.

[0019] The third aspect of the present invention provides a hot-melt benzoxazine resin prepreg:

[0020] It comprises the above-mentioned hot-melt benzoxazine resin composition and a reinforcing material; the mass percentage of the reinforcing material in the hot-melt benzoxazine resin prepreg is 60%-65%.

[0021] Preferably, the reinforcing material is fiber cloth; the fiber cloth is one of carbon fiber, glass fiber, aramid, PBO fiber and basalt fiber; the fiber state of the fiber cloth is one of unidirectional, plain weave, forged weave and twill weave.

[0022] A fourth aspect of the present invention provides a method for preparing the hot-melt benzoxazine resin prepreg as described above, comprising the following steps:

[0023] The benzoxazine resin composition is coated into a film by a hot melt prepreg process; the benzoxazine resin composition coated into a film is hot pressed and compounded with the reinforcing material to obtain the hot melt benzoxazine resin prepreg;

[0024] When the benzoxazine resin composition is coated into a film, the coating temperature is 55-85° C., and the glue content is 35%-40%; when the benzoxazine resin composition coated into a film is hot-pressed and composited with the reinforcing material, the pressing temperature is 75-95° C.

[0025] A fifth aspect of the present invention provides a benzoxazine resin-based composite material, which is prepared using the above-mentioned hot-melt benzoxazine resin prepreg.

[0026] A sixth aspect of the present invention provides a method for preparing the benzoxazine resin-based composite material as described above, comprising the following steps:

[0027] The hot-melt benzoxazine resin prepreg as described above is autoclaved or compression molded to obtain the benzoxazine resin-based composite material; the pressure of the autoclave molding or compression molding is 0.55-0.76 MPa, and the curing temperature is 165-195°C. When the autoclave molding process is adopted, the vacuum state should be maintained throughout the process; when the compression molding process is adopted, the air is exhausted 1-3 times when the curing temperature is stable, the total curing time is 150-190 min, the cooling rate does not exceed 3°C / min, and the temperature is cooled to below 65°C, the pressure is released, and the benzoxazine resin-based composite material is taken out.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The hot-melt benzoxazine resin composition of the present invention uses a diamine benzoxazine resin as the main body to ensure the temperature resistance of the resin matrix, and introduces one or more of the following epoxy resins: AG-80 aliphatic epoxy resin, AFG-90, and TDE-85 mixed epoxy resin to improve the processability of the benzoxazine resin while ensuring the temperature resistance of the matrix. Under heating conditions, the epoxy resin and the curing agent can react in advance, and the active groups of the ring-opening reaction of the epoxy resin can induce the ring-opening of the oxazine ring at the same time, thereby promoting the curing reaction of the benzoxazine resin, while reducing the curing temperature of the resin matrix and increasing the viscosity of the resin matrix during the curing process, thereby achieving "zero" glue absorption during the curing of the prepreg, greatly improving the low viscosity of the benzoxazine resin at high temperature and the lack of glue in composite products. , the problem of insufficient interlayer bonding performance. Due to the introduction of epoxy resin, the flame retardant performance of the resin matrix cannot be guaranteed to meet the aviation grade requirements. Therefore, flame retardants are introduced into it to optimize the flame retardant performance of the resin matrix. The curing agent is of medium and low temperature type, and is used with epoxy resin to adjust the resin viscosity and curing temperature. By controlling the amount of addition, it can be ensured that the resin matrix has good latency while achieving the purpose of lowering the curing temperature of the resin matrix. The addition of epoxy diluent is mainly used to improve the room temperature viscosity of benzoxazine resin, solve the problem that the prepared prepreg is non-sticky, the prepreg paving operation process is poor, and it is difficult to complete the paving of composite materials with complex configurations. The toughening agent is selected from engineering plastics to improve the brittleness of the resin matrix cured product while maintaining the heat resistance of the resin matrix.

[0030] The present invention provides a complete production process for prepregs and composite materials, and successfully prepares high-performance benzoxazine resin systems, prepregs and composite materials. The resin has low curing temperature, good film-forming properties and high latency, the prepreg has precise control of the glue content, and the composite material has strong mechanical properties, good flame retardancy, low product porosity and the like, meeting the requirements of aviation applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a graph showing the glass transition temperature performance test results of the resin composition prepared in Example 1 of the present invention;

[0032] Figure 2 is a DSC graph of the resin composition obtained in Example 1 of the present invention;

[0033] Figure 3 is a viscosity-temperature curve of the resin composition obtained in Example 1 of the present invention;

[0034] Figure 4 This is a picture of the finished prepreg prepared in Example 8 of the present invention.

[0035] Figure 5 This is the morphology of the composite material prepared in Example 10 of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] A first aspect of an embodiment of the present invention provides a hot-melt benzoxazine resin composition, comprising the following components in parts by weight:

[0038] 30-80 parts of benzoxazine resin, 10-50 parts of epoxy resin, 10-30 parts of toughening agent, 2-15 parts of flame retardant, 10-25 parts of curing accelerator and 1-15 parts of epoxy diluent.

[0039] The hot-melt benzoxazine resin composition of the embodiment of the present invention is mainly composed of diamine benzoxazine resin to ensure the temperature resistance of the resin matrix, and epoxy resin is introduced to improve the processability of the benzoxazine resin while ensuring the temperature resistance of the matrix. Under heating conditions, the epoxy resin and the curing agent can react in advance, and the active groups of the ring-opening reaction of the epoxy resin can induce the ring-opening of the oxazine ring at the same time, promoting the curing reaction of the benzoxazine resin, while reducing the curing temperature of the resin matrix and increasing the viscosity of the resin matrix during the curing process, achieving "zero" glue absorption during the curing of the prepreg, greatly improving the low viscosity of the benzoxazine resin at high temperature, lack of glue in composite products, and insufficient interlayer bonding performance. With the introduction of epoxy resin, the flame retardant properties of the resin matrix cannot meet the aviation grade requirements, so flame retardants are introduced to optimize the flame retardant properties of the resin matrix. The curing agent is of medium and low temperature type, and is used with epoxy resin to adjust the resin viscosity and curing temperature. By controlling the amount of addition, it can be ensured that the resin matrix has good latency while achieving the purpose of lowering the curing temperature of the resin matrix. The addition of epoxy diluent is mainly used to improve the room temperature viscosity of benzoxazine resin, solve the problem that the prepared prepreg is non-sticky, the prepreg laying operation process is poor, and it is difficult to complete the laying of composite parts with complex configurations. The toughening agent can improve the brittleness of the resin matrix cured product while maintaining the heat resistance of the resin matrix.

[0040] In some embodiments, the benzoxazine resin comprises 70 parts, the epoxy resin comprises 15-30 parts, the toughening agent comprises 10-20 parts, the flame retardant comprises 10-15 parts, the curing accelerator comprises 20-25 parts, and the epoxy diluent comprises 10-15 parts.

[0041] In some embodiments, the benzoxazine resin is a diamine-type benzoxazine resin; the epoxy resin is a mixture of one or more of AG-80 aliphatic epoxy resin, AFG-90 or TDE-85 mixed epoxy resin; the toughening agent is one or more of PEEK, PES, PSF and PEI; the flame retardant is one or more of aluminum hydroxide, magnesium hydroxide, magnesium oxide, ammonium polyphosphate, tetrabromobisphenol A and decabromodiphenylethane; the curing accelerator is one or more of aliphatic amines, alicyclic amines, aromatic amines, imidazoles, diethylimidazoles and methylimidazoles; the epoxy diluent is one or more of ED-503, ED-506, ED-523T, ED-509S, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether and neopentyl glycol diglycidyl ether.

[0042] A second aspect of an embodiment of the present invention provides a method for preparing the above-mentioned hot-melt benzoxazine resin composition, comprising the following steps:

[0043] The benzoxazine resin is melted; and the melted benzoxazine resin is mixed with the epoxy resin, the toughening agent, the flame retardant, the curing accelerator and the epoxy diluent to obtain the hot-melt benzoxazine resin composition.

[0044] In some embodiments, the method for preparing a hot-melt benzoxazine resin composition specifically comprises the following steps:

[0045] S1: melting the benzoxazine resin;

[0046] S2: melting the toughening agent into the epoxy resin;

[0047] S3: mixing the melted benzoxazine resin, the toughening agent melted in the epoxy resin, the flame retardant, the epoxy diluent and the curing accelerator;

[0048] S4: grinding the obtained mixture to obtain the benzoxazine resin composition;

[0049] The heating temperature when melting the benzoxazine resin in step S1 is 60-140° C., and the heating time is 1-4 h; the melting temperature when melting the toughening agent in the epoxy resin in step S2 is 100-150° C.; when grinding the mixture in step S4, the number of roller grinding times is 1-4 times.

[0050] A third aspect of an embodiment of the present invention provides a hot-melt benzoxazine resin prepreg:

[0051] It comprises the above-mentioned hot-melt benzoxazine resin composition and a reinforcing material; the mass percentage of the reinforcing material in the hot-melt benzoxazine resin prepreg is 60%-65%.

[0052] In some embodiments, the reinforcing material is fiber cloth; the fiber cloth is one of carbon fiber, glass fiber, aramid, PBO fiber and basalt fiber; the fiber state of the fiber cloth is one of unidirectional, plain weave, forged weave and twill weave.

[0053] A fourth aspect of an embodiment of the present invention provides a method for preparing the hot-melt benzoxazine resin prepreg as described above, comprising the following steps:

[0054] The benzoxazine resin composition is coated into a film by a hot melt prepreg process; the benzoxazine resin composition coated into a film is hot pressed and compounded with the reinforcing material to obtain the hot melt benzoxazine resin prepreg;

[0055] When the benzoxazine resin composition is coated into a film, the coating temperature is 55-85° C., and the glue content is 35%-40%; when the benzoxazine resin composition coated into a film is hot-pressed and composited with the reinforcing material, the pressing temperature is 75-95° C.

[0056] A fifth aspect of the embodiments of the present invention provides a benzoxazine resin-based composite material, which is prepared using the above-mentioned hot-melt benzoxazine resin prepreg.

[0057] A sixth aspect of an embodiment of the present invention provides a method for preparing the benzoxazine resin-based composite material as described above, comprising the following steps:

[0058] The hot-melt benzoxazine resin prepreg as described above is autoclaved or compression molded to obtain the benzoxazine resin-based composite material; the pressure of the autoclave molding or compression molding is 0.55-0.76 MPa, and the curing temperature is 165-195°C. When the autoclave molding process is adopted, the vacuum state should be maintained throughout the process; when the compression molding process is adopted, the air is exhausted 1-3 times when the curing temperature is stable, the total curing time is 150-190 min, the cooling rate does not exceed 3°C / min, and the temperature is cooled to below 65°C, the pressure is released, and the benzoxazine resin-based composite material is taken out.

[0059] Example 1

[0060] The hot-melt benzoxazine resin composition of this embodiment includes the following components in parts by weight:

[0061] 70 parts of MDA type benzoxazine resin, 30 parts of AG-80 epoxy resin, 20 parts of PEEK toughener, 10 parts of decabromodiphenylethane, 5 parts of tetrabromobisphenol A, 20 parts of dicyandiamide curing accelerator, and 10 parts of 1,4-butanediol diglycidyl ether epoxy diluent.

[0062] The preparation method of the hot-melt benzoxazine resin composition of this embodiment comprises the following steps:

[0063] In a stirring kettle at 160°C, AG-80 epoxy resin and PEEK toughening agent were mixed, and the powder dissolution state inside the mixture was observed. When the mixture showed a uniform phase and no obvious particles, the mixture was discharged and placed in an oven at 60±5°C for insulation and reserved; the MDA type benzoxazine resin was placed in an oven at 60°C for preheating for 1 h in advance; the mold temperature controller was turned on and set to 60°C, and the planetary agitator was preheated in advance. When the planetary agitator was kept clean, the preheated benzoxazine resin, the mixture of AG-80 epoxy resin and PEEK toughening agent, and 1,4-butanediol diglycidyl ether were added to the planetary agitator, stirred and dispersed, and stirred at 60±3°C for 30±5 min; after the stirring was completed, the temperature of the mold temperature controller was adjusted to 45°C, tetrabromobisphenol A, decabromodiphenylethane, and dicyandiamide were added in sequence, and stirring and dispersion were continued. Stirring was continued at 45°C for 15 min; discharge the material, repeat the roller pass 4 times, take a proper amount of the material after the roller pass for performance test, and wrap the rest in a plastic bag, heat seal it and put it into a cold storage to obtain a hot melt benzoxazine resin composition. The glass transition temperature performance test results of the prepared hot melt benzoxazine resin composition are as follows Figure 1 As shown in the DSC diagram Figure 2 As shown in the figure, the viscosity-temperature curve is as follows Figure 3 shown.

[0064] Example 2

[0065] The hot-melt benzoxazine resin composition of this embodiment includes the following components in parts by weight:

[0066] 70 parts of MDA type benzoxazine resin, 20 parts of 128 epoxy resin, 10 parts of 1,4-butanediol diglycidyl ether epoxy diluent, 15 parts of PES toughening agent, 10 parts of magnesium oxide, and 20 parts of dicyandiamide curing accelerator.

[0067] The preparation method of the hot-melt benzoxazine resin composition of this embodiment comprises the following steps:

[0068] In a stirring kettle at 160°C, 128 epoxy resin and PES toughening agent were mixed, and the powder dissolution state inside the mixture was observed. When the mixture was uniform and had no obvious particles, the mixture was discharged and placed in an oven at 60±5°C for insulation and reserved. The MDA type benzoxazine resin was placed in an oven at 60°C for preheating for 1 h in advance. The mold temperature controller was turned on and set to 60°C, and the planetary agitator was preheated in advance. When the planetary agitator was kept clean, the preheated benzoxazine resin, the mixture of 128 epoxy resin and PES toughening agent, and 1,4-butanediol diglycidyl ether were added to the planetary agitator, stirred and dispersed, and stirred at 60±3°C for 30±5 min; after the stirring is completed, the temperature of the mold temperature controller is adjusted to 45°C, and the weighed amounts of magnesium oxide and dicyandiamide are added in turn, and the stirring and dispersion are continued. Stirring is carried out at 45°C for 15 minutes; the material is discharged, and the roller is repeated 4 times. An appropriate amount of the material after the roller is taken for performance testing, and the rest is wrapped in a plastic bag, heat-sealed, and put into a cold storage to obtain a hot-melt benzoxazine resin composition.

[0069] Example 3

[0070] The hot-melt benzoxazine resin composition of this embodiment includes the following components in parts by weight:

[0071] 70 parts of MDA type benzoxazine resin, 15 parts of AFG-90 epoxy resin, 15 parts of 1,4-butanediol diglycidyl ether epoxy diluent, 15 parts of PES toughening agent, 10 parts of aluminum hydroxide flame retardant, and 20 parts of dicyandiamide curing accelerator.

[0072] The preparation method of the hot-melt benzoxazine resin composition of this embodiment comprises the following steps:

[0073] In a stirring kettle at 160°C, AFG-90 epoxy resin and PES toughening agent were mixed, and the powder dissolution state inside the mixture was observed. When the mixture showed a uniform phase and no obvious particles, the mixture was discharged and placed in an oven at 60±5°C for insulation and reserved; the MDA type benzoxazine resin was placed in an oven at 60°C for preheating for 1.5 h in advance; the mold temperature controller was turned on and set to 60°C, and the planetary agitator was preheated in advance. When the planetary agitator was kept clean, the preheated benzoxazine resin, the mixture of AG-90 epoxy resin and PES toughening agent, and 1,4-butanediol diglycidyl ether were added to the planetary agitator, stirred and dispersed, and stirred at 60±3°C for 30±5 min; after the stirring was completed, the temperature of the mold temperature controller was adjusted to 45°C, and the weighed amounts of aluminum hydroxide and dicyandiamide were added in turn, and stirring and dispersion continued. Stirring at 45°C for 15 min; discharge the material, repeat the roller process 4 times, take a proper amount of the material after the roller process for performance testing, and wrap the rest in a plastic bag, heat-seal it, and put it into a cold storage to obtain a hot-melt benzoxazine resin composition.

[0074] Example 4

[0075] The hot-melt benzoxazine resin composition of this embodiment includes the following components in parts by weight:

[0076] 70 parts of MDA type benzoxazine resin, 15 parts of AG-80 epoxy resin, 15 parts of 1,4-butanediol diglycidyl ether epoxy diluent, 10 parts of PEEK toughening agent, 5 parts of aluminum hydroxide and 5 parts of tetrabromobisphenol A, and 25 parts of dicyandiamide curing accelerator.

[0077] The preparation method of the hot-melt benzoxazine resin composition of this embodiment comprises the following steps:

[0078] In a stirring kettle at 160°C, AG-80 epoxy resin and PEEK toughening agent were mixed, and the powder dissolution state inside the mixture was observed. When the mixture showed a uniform phase and no obvious particles, the mixture was discharged and placed in an oven at 60±5°C for insulation and reserved; the MDA type benzoxazine resin was placed in an oven at 60°C for preheating for 1.5 h in advance; the mold temperature controller was turned on and set to 60°C, and the planetary agitator was preheated in advance. When the planetary agitator was kept clean, the preheated benzoxazine resin, the mixture of AG-80 epoxy resin and PEEK toughening agent, and 1,4-butanediol diglycidyl ether were added to the planetary agitator, stirred and dispersed, and stirred at 60±3°C for 30±5 min; after the stirring was completed, the temperature of the mold temperature controller was adjusted to 45°C, and the weighed aluminum hydroxide, tetrabromobisphenol A, and dicyandiamide were added in turn, and continued to stir and disperse, and stirred at 45°C for 15 min; discharge the material, repeat the roller process 4 times, take a proper amount of the material after the roller process for performance testing, and wrap the rest in a plastic bag, heat-seal it, and put it into a cold storage to obtain a hot-melt benzoxazine resin composition.

[0079] Example 5

[0080] The hot-melt benzoxazine resin composition of this embodiment includes the following components in parts by weight:

[0081] 80 parts of MDA type benzoxazine resin, 50 parts of AFG-90 epoxy resin, 15 parts of 1,4-butanediol diglycidyl ether epoxy diluent, 30 parts of PES toughening agent, 15 parts of aluminum hydroxide flame retardant, and 25 parts of dicyandiamide curing accelerator.

[0082] The preparation method of the hot-melt benzoxazine resin composition of this embodiment comprises the following steps:

[0083] In a stirring kettle at 160°C, AG-80 epoxy resin and PES toughening agent were mixed, and the powder dissolution state inside the mixture was observed. When the mixture showed a uniform phase and no obvious particles, the mixture was discharged and placed in an oven at 60±5°C for insulation and reserved; the MDA type benzoxazine resin was placed in an oven at 60°C for preheating for 1.5 h in advance; the mold temperature controller was turned on and set to 60°C, and the planetary agitator was preheated in advance. When the planetary agitator was kept clean, the preheated benzoxazine resin, the mixture of AG-90 epoxy resin and PES toughening agent, and 1,4-butanediol diglycidyl ether were added to the planetary agitator, stirred and dispersed, and stirred at 60±3°C for 30±5 min; after the stirring was completed, the temperature of the mold temperature controller was adjusted to 45°C, and the weighed amounts of aluminum hydroxide and dicyandiamide were added in turn, and stirring and dispersion was continued. Stirring was continued at 45°C for 15 min; discharge the material, repeat 4 times, take a proper amount of the material after the roller for performance test, and wrap the rest in a plastic bag, heat-seal it and put it into a cold storage to obtain a hot-melt benzoxazine resin composition.

[0084] Example 6

[0085] The hot-melt benzoxazine resin composition of this embodiment includes the following components in parts by weight:

[0086] 30 parts of MDA type benzoxazine resin, 10 parts of AFG-90 epoxy resin, 1 part of 1,4-butanediol diglycidyl ether epoxy diluent, 10 parts of PES toughening agent, 2 parts of aluminum hydroxide flame retardant, and 10 parts of dicyandiamide curing accelerator.

[0087] The preparation method of the hot-melt benzoxazine resin composition of this embodiment comprises the following steps:

[0088] In a stirring kettle at 160°C, AG-80 epoxy resin and PES toughening agent were mixed, and the powder dissolution state inside the mixture was observed. When the mixture showed a uniform phase and no obvious particles, the mixture was discharged and placed in an oven at 60±5°C for insulation and reserved; the MDA type benzoxazine resin was placed in an oven at 60°C for preheating for 1.5 h in advance; the mold temperature controller was turned on and set to 60°C, and the planetary agitator was preheated in advance. When the planetary agitator was kept clean, the preheated benzoxazine resin, the mixture of AG-90 epoxy resin and PES toughening agent, and 1,4-butanediol diglycidyl ether were added to the planetary agitator, stirred and dispersed, and stirred at 60±3°C for 30±5 min; after the stirring was completed, the temperature of the mold temperature controller was adjusted to 45°C, and the weighed amounts of aluminum hydroxide and dicyandiamide were added in turn, and stirring and dispersion was continued. Stirring was continued at 45°C for 15 min; discharge the material, repeat 4 times, take a proper amount of the material after the roller for performance test, and wrap the rest in a plastic bag, heat-seal it and put it into a cold storage to obtain a hot-melt benzoxazine resin composition.

[0089] Example 7

[0090] The hot-melt benzoxazine resin prepreg of this embodiment includes the benzoxazine resin composition of Example 1 and glass fiber cloth. The content of the benzoxazine resin composition in the prepreg is 40%.

[0091] The preparation method of the hot-melt benzoxazine resin prepreg of this embodiment comprises the following steps:

[0092] The benzoxazine resin composition prepared in Example 1 was preheated at 65° C. to melt it; the benzoxazine resin composition was coated into a film of uniform thickness at 75° C.; the plain alkali-free glass fiber was placed between the two layers of the film, and the two layers were hot-pressed by a roller at 85° C. to obtain a benzoxazine resin prepreg with a glue content of 40%.

[0093] Example 8

[0094] The hot-melt benzoxazine resin prepreg of this embodiment includes the benzoxazine resin composition of Example 2 and carbon fiber cloth, and the content of the benzoxazine resin composition in the prepreg is 40%.

[0095] The preparation method of the hot-melt benzoxazine resin prepreg of this embodiment comprises the following steps:

[0096] The benzoxazine resin system prepared in Example 2 was preheated at 65°C to melt it; the benzoxazine resin system was coated at 75°C to form a film of uniform thickness; the satin-woven carbon fiber was arranged between the two layers of film, and roller hot-pressed at 85°C to obtain a hot-melt benzoxazine resin prepreg with a glue content of 40%. The finished hot-melt benzoxazine resin prepreg is shown in the figure below. Figure 4 shown.

[0097] Example 9

[0098] The hot-melt benzoxazine resin prepreg of this embodiment includes the benzoxazine resin composition of Example 3 and glass fiber cloth. The content of the benzoxazine resin composition in the prepreg is 40%.

[0099] The preparation method of the hot-melt benzoxazine resin prepreg of this embodiment comprises the following steps:

[0100] The benzoxazine resin system prepared in Example 3 was preheated at 65° C. to melt it; the benzoxazine resin system was coated into a film of uniform thickness at 75° C.; the satin-woven glass fiber was arranged between the two layers of the film, and roller hot-pressed and laminated at 85° C. to obtain a prepreg with a glue content of 40%.

[0101] Example 10

[0102] The benzoxazine resin-based composite material of this embodiment is prepared by using the benzoxazine resin prepreg in Example 8.

[0103] The preparation method of the benzoxazine resin-based composite material of this embodiment comprises the following steps:

[0104] The benzoxazine resin prepreg is laminated and formed into a laminate using an autoclave. The laid laminate is placed in the designated position. Before the laminate is cured, the vacuum bag airtightness check should be carried out, that is, when the vacuum line is closed, the leakage of each component should be checked, and the drop in vacuum degree within 5 minutes should not be greater than 17kPa; the positive pressure of the autoclave is 0.65 MPa. The vacuum bag remains in a evacuated state during the entire curing process until the curing is completed. When the pressure of the autoclave reaches 0.65 MPa, heating begins with a heating rate of 1°C / min, and the curing is carried out at 180°C and 0.65 MPa tank pressure for 180 min; after that, the temperature is lowered with the furnace, and the pressure is released and the tank is opened when the temperature drops below 65°C. A benzoxazine resin-based composite material is obtained. The morphology of the obtained benzoxazine resin-based composite material is as shown Figure 5 shown.

[0105] Comparative Example 1

[0106] The benzoxazine resin composition of this comparative example is different from that of Example 1 in that no epoxy resin is added, and the remaining components and contents are the same as those of Example 1. The preparation method of the benzoxazine resin composition of this comparative example is the same as that of Example 1.

[0107] It can be seen from the following experimental data that the benzoxazine resin composition of the present invention has good process matching for preparing prepreg by hot melt method, and the resin has relatively low curing temperature, good viscosity at room temperature, and good film-forming property; the glue content of the prepreg is easy to control, the volatile content is low, and there are many types of reinforced fabrics to choose from; the composite material prepared by using the prepreg has excellent mechanical properties, low porosity, and excellent flame retardant properties.

[0108] Table 1 Resin curing temperature data of each example

[0109]

[0110] Table 2 Basic performance test results of the laminates prepared in each embodiment

[0111]

[0112] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A hot-melt benzoxazine resin composition, characterized in that: The composition includes the following components in parts by weight: 70 parts of benzoxazine resin, 15-30 parts of epoxy resin, 10-20 parts of toughening agent, 10-15 parts of flame retardant, 20-25 parts of curing accelerator and 10-15 parts of epoxy diluent; the epoxy resin is one or a mixture of AG-80 aliphatic epoxy resin, AFG-90 or TDE-85 mixed epoxy resin; The benzoxazine resin is a diamine type benzoxazine resin; The epoxy diluent is one or more of ED-503, ED-506, ED-523T, ED-509S, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether and neopentyl glycol diglycidyl ether; The toughening agent is one or more of PEEK, PES, PSF and PEI; the flame retardant is one or more of aluminum hydroxide, magnesium hydroxide, magnesium oxide, ammonium polyphosphate, tetrabromobisphenol A and decabromodiphenylethane; the curing accelerator is one or more of aliphatic amines, alicyclic amines, aromatic amines, imidazole, diethylimidazole and methylimidazole.

2. A method for preparing a hot-melt benzoxazine resin composition as claimed in claim 1, characterized in that: The steps include: The benzoxazine resin is melted; and the melted benzoxazine resin is mixed with the epoxy resin, the toughening agent, the flame retardant, the curing accelerator and the epoxy diluent to obtain the hot-melt benzoxazine resin composition.

3. The method for preparing a hot-melt benzoxazine resin composition according to claim 2, characterized in that: The specific steps include: S1: melting the benzoxazine resin; S2: melting the toughening agent into the epoxy resin; S3: mixing the melted benzoxazine resin, the toughening agent melted in the epoxy resin, the flame retardant, the epoxy diluent and the curing accelerator; S4: grinding the obtained mixture to obtain the benzoxazine resin composition; The heating temperature when melting the benzoxazine resin in step S1 is 60-140° C., and the heating time is 1-4 h; the melting temperature when melting the toughening agent in the epoxy resin in step S2 is 100-150° C.; when grinding the mixture in step S4, the number of roller grinding times is 1-4 times.

4. A hot melt benzoxazine resin prepreg, characterized in that: The invention comprises the hot-melt benzoxazine resin composition as claimed in claim 1 and a reinforcing material; the mass percentage of the reinforcing material in the hot-melt benzoxazine resin prepreg is 60%-65%.

5. The hot-melt benzoxazine resin prepreg according to claim 4, characterized in that: The reinforcing material is a fiber cloth; the fiber cloth is one of carbon fiber, glass fiber, aramid, PBO fiber and basalt fiber; the fiber state of the fiber cloth is one of unidirectional, plain weave, forged weave and twill weave.

6. A method for preparing a hot-melt benzoxazine resin prepreg as claimed in claim 4 or 5, comprising the following steps: The benzoxazine resin composition is coated into an adhesive film by a hot melt prepreg process; Hot-pressing and compounding the benzoxazine resin composition coated into an adhesive film with the reinforcing material to obtain the hot-melt benzoxazine resin prepreg; When the benzoxazine resin composition is coated into a film, the coating temperature is 55-85° C., and the glue content is 35%-40%; when the benzoxazine resin composition coated into a film is hot-pressed and composited with the reinforcing material, the pressing temperature is 75-95° C.

7. A benzoxazine resin-based composite material, characterized in that: The method is prepared by using the hot-melt benzoxazine resin prepreg as described in claim 4 or 5.

8. A method for preparing a benzoxazine resin-based composite material according to claim 7, characterized in that: The following steps are involved: The hot-melt benzoxazine resin prepreg as claimed in claim 4 or 5 is formed by autoclave or compression molding to obtain the benzoxazine resin-based composite material; the pressure of the autoclave molding or compression molding is 0.55-0.76 MPa, and the curing temperature is 165-195°C. When the autoclave molding process is adopted, the vacuum state should be maintained throughout the process; when the compression molding process is adopted, the air is exhausted 1-3 times when the curing temperature is stable, the total curing time is 150-190 min, the cooling rate does not exceed 3°C / min, and when the temperature drops below 65°C, the pressure is released to take out the benzoxazine resin-based composite material.

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